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United States Patent |
5,186,904
|
Lyzinski
,   et al.
|
February 16, 1993
|
Laboratory simulator of reactor for a petroleum refinery
Abstract
A laboratory instrument provides a small model reactor which better
simulates a back mixed reactor containing a catalyst. The reactor is
especially valuable for simulating commercial scale hydrotreating of
petroleum resid, coal, and other non-distillable hydrocarbons to obtain
some distillable products. An important feature is a magnetically driven
pump completely enclosed within the reactor shell of the simulator. All
embodiments provide a high temperature and pressure, low liquid to
catalyst volume, model reactor where an entire process is carried out
within the simulator shell under substantially the conditions prevailing
in the full scale reactor.
Inventors:
|
Lyzinski; David (Wheaton, IL);
Buttke; Robert D. (Naperville, IL);
Taylor; James L. (Naperville, IL);
Hall; William M. (Batavia, IL)
|
Assignee:
|
Amoco Corporation (Chicago, IL)
|
Appl. No.:
|
397390 |
Filed:
|
August 23, 1989 |
Current U.S. Class: |
422/130; 208/143; 208/146; 208/157; 417/420; 422/140; 422/143 |
Intern'l Class: |
B01J 019/00 |
Field of Search: |
422/130,140,143
208/143,146,157
417/420
|
References Cited
U.S. Patent Documents
4111614 | Sep., 1978 | Martin et al. | 417/420.
|
4556537 | Dec., 1985 | Honma | 422/130.
|
4559132 | Dec., 1985 | Kuehler | 208/158.
|
4684456 | Aug., 1987 | Van Driesen et al. | 208/143.
|
4753721 | Jun., 1988 | McDaniel et al. | 208/143.
|
4902407 | Feb., 1990 | Chan et al. | 208/146.
|
Other References
Industrial and Engineering Chemistry, vol. 57, No. 4, Apr. 1965,
"Micropiloting", pp. 61-63.
|
Primary Examiner: Warden; Robert J.
Assistant Examiner: McMahon; Timothy M.
Attorney, Agent or Firm: McDonald; Scott P., Kretchmer; Richard A., Sroka; Frank J.
Claims
The claimed invention is:
1. An ebullated bed laboratory reactor for simulating a process and
operating conditions of a full scale ebullated bed reactor in a petroleum
refinery having a feed for oil and hydrogen containing gas, said
laboratory reactor comprising:
a reactor shell means assembled from a plurality of housing parts for
providing a reaction zone and for enabling an emplacement of catalyst into
and removing and replacing catalyst from said reaction zone by at least
partially disassembling and reassembling said housing;
feed means connected to said reactor shell for feeding oil and a
hydrogen-containing gas to said reaction zone at a particular rate which
substantially simulates a corresponding rate at which said oil and gas is
fed into a full scale ebullated bed reactor;
internal recycle displacement pump means operatively positioned within said
reactor shell for substantially back mixing said oil feed and said gas in
a presence of said catalyst, under a catalyst to liquid ratio fluid
displacement and at a pressure and temperature substantially similar to a
ratio, pressure, and temperature used in said full scale ebullated bed
reactor in order to produce upgraded oil and product gases; and
a product outlet line connected to said reactor shell for removing said
upgraded oil and said product gases from said shell.
2. The laboratory reactor of claim 1 wherein said plurality of housing
parts which may be assembled to form a reactor shell comprises:
a plurality of pipe-like segments joined together to form a miniature model
for providing internal conditions which are a simulation of corresponding
conditions prevailing in a full scale ebullated bed hydrotreating reactor,
with said internal recycle pump means located at a top of said model;
said oil comprises a carbonaceous material selected from the group
consisting of resid oil, a petroleum fraction having a boiling point of at
least 650.degree. F., coal liquids, coal, bitumen, tar sands oil, and
shale oil; and
said catalyst comprises a hydrotreating catalyst.
3. The laboratory reactor of claim 1 wherein said pump means comprises a
positive displacement pump.
4. The laboratory reactor of claim 1 wherein said pump has drive means
extending outwardly of said shell and spaced from said reaction zone for
substantially isolating said drive means from said pressure and
temperature of said reaction zone.
5. The laboratory reactor of claim 4 wherein said drive means comprises a
magnetic coupling drive.
6. The laboratory reactor of claim 1 including a pair of screen means
partitioning an interior of said assembled housing to contain a top and
bottom of a bed of said catalyst.
7. The laboratory reactor of claim 1 including catalyst spacer means within
said shell positioned away from said reaction zone for containing a top
and bottom of a bed of said catalyst and for enhancing the thermal
stability of said reaction zone.
8. The laboratory reactor of claim 1 wherein said pump means comprises a
magnetically driven pump, a recycle line, and at least one slip joint for
detachably connecting said recycle line to said pump, all contained within
said assembled housing.
9. The laboratory reactor of claim 8 wherein said pump means comprises a
displacement gear pump.
10. The laboratory reactor of claim 8 wherein said pump means include speed
control means for controlling a rate of said back mixing within said
assembled housing.
11. A high temperature and pressure, low liquid to catalyst volume small
model simulator for reproducing an approximation of a resid refining
process carried out in a full scale ebullated bed resid hydrotreating
reactor, said full scale reactor having a temperature and pressure at
which reaction is carried out, said simulator comprising a miniature
reactor shell containing entirely therein, a plurality of internal parts
including at least a pump and magnetic drive means for said pump, and
means for controlling an amount of recirculating back mix produced within
said simulator by controlling a speed of said pump, whereby an entire
refining process is carried out within said miniature shell at the
temperature and pressure established therein which substantially simulates
the temperature and pressure in a full scale reactor shell.
12. The simulator of claim 11 further comprising means for suspending and
containing both a top and bottom of a catalytic bed within said reactor
shell for said pump to circulate and recirculate a product feed stream
through said catalytic bed.
13. The simulator of claim 12 wherein said miniature reactor shell is
assembled from a plurality of shell parts, and means for clamping said
plurality of shell parts together in order to form said miniature reactor
shell whereby said miniature reactor shell may be disassembled to provide
easy access for catalyst replacement inside said shell.
14. The simulator of claim 12 wherein said suspending and containing means
further comprises catalyst spacer means inside said shell for helping to
maintain thermal stability within said shell.
15. The simulator of claim 12 further comprising means for sliding said
internal parts of said reactor into said miniature shell whereby said
internal parts within said shell may be replaced by slidingly removing and
replacing said sliding parts.
16. A miniature laboratory reactor for simulating a process of a full scale
ebullated bed reactor, said laboratory reactor having a closed container
held in an upright position by a support means; an insert slidably mounted
inside said container; said insert including at least a positive
displacement pump, a magnetic drive for said pump entirely included within
said container so that said pump operates entirely within environmental
conditions prevailing within said container while being driven from
outside said housing via said magnetic drive; a catalytic bed having a top
and a bottom inside said container; means for inserting a feedstream into
said container at a point near the bottom of said catalytic bed; means for
removing a liquid stream which is derived from said inserted feedstream
from said container at a point adjacent the top of said catalytic bed; and
means including said pump for drawing at least a part of said liquid
stream from above said catalytic bed and for reinserting said part of said
liquid stream adjacent the bottom of said catalytic bed, thereby
recirculating and back mixing at least said part of said liquid stream
with said inserted feedstream.
17. A laboratory reactor for simulating a process and operating conditions
prevailing in a full scale ebullated bed reactor in a petroleum refinery,
said full scale reactor operating at substantially an internal pressurized
and temperature and having a feed by which oil and a hydrogen containing
gas are introduced into said full scale reactor in order to maintain a
predetermined catalyst to liquid ratio within said full scale reactor,
said laboratory reactor comprising:
a reactor shell providing a reaction zone containing a catalyst means, said
reactor being a housing that can contain substantially said internal
pressure and temperature of said full scale reactor and which can be
opened for cleaning and servicing;
means connected to said reactor shell for feeding oil and a
hydrogen-containing gas into said reaction zone at a rate which is
substantially similar to the corresponding rate used in a full scale
reactor;
means positioned within said reactor shell for substantially back mixing
said feed of oil and gas in a presence of said catalyst under a catalyst
to liquid ratio and at a pressure and temperature which is substantially
similar to a corresponding ratio, pressure, and temperature used in said
full scale reactor in order to produce upgraded oil and product gases; and
means coupled to said reactor shell for removing said upgraded oil and said
product gases from said shell.
Description
This invention relates to laboratory instruments and more particularly to
instruments for simulating and piloting reactors used in a petroleum
refinery--especially, although not exclusively, an ebullated resid
hydrotreating reactor.
For convenience of expression, terms such as "resid", "petroleum" or "oil"
will be used hereinafter. However, as those skilled in the art know, there
are a number of carbonaceous materials which may be included with these
terms. Therefore, these terms are to be construed as including all
suitable carbonaceous materials such as those in the group consisting of
resid oil, a petroleum fraction having a boiling point of at least
650.degree. F., coal liquids, coal, bitumen, tar sands oil, and shale oil.
Refining units have been built without pilot plant reactors. However, such
construction often leads to inefficiencies and failure to attain the
desired designs and product output.
Reference may be made to U.S. Pat. No. 4,753,721 for an example of a
petroleum refinery reactor which the inventive instrument may simulate.
This patent shows a resid refining unit, wherein an ebullating or expanded
bed reactor may be in the order of six or seven stories tall. In this
large dimension, it is possible to build many things into the reactor
which can not be exactly duplicated in prior art laboratory instruments.
The cost of such a refining unit is measured in the hundreds of millions
of dollars. When it is necessary or desirable to design or to improve such
a refining unit, it should be possible to test processes, theories,
practices, and procedures in a laboratory on a small model simulation of
the refining unit, before the hundreds of millions of dollars are
committed to construction.
However, in the past, only an approximation of an ebullated bed
hydrotreating unit has been available prior to a commitment of substantial
sums to actual construction. This led to a need for a long and expensive
trial and correction period after construction and before a full on-stream
refinery operation was attained at design efficiency.
By way of example, U.S. Pat. No. 4,753,721 explains that the refinery uses
ebullating bed reactors to process 1000.sup.+ .degree. F. oil. However, it
has not been possible to make a small model ebullated bed reactor which
could perform the entire reactor process at actual operating conditions.
Accordingly, the laboratory practice has been to heat and cool a product
stream in a small model refining unit so that the stream was about
700.degree. to 900.degree. F. where the oil was in contact with the
catalyst and about 350.degree. F. where the oil was in contact with a
recycle pump. Then, the test results taken at such varying temperatures
have been extrapolated in an effort to predict what would happen in the
full scale reactor where all processing is carried out at actual operating
conditions.
One of the difficulties with heating and cooling the product stream has
been that the cooling has precipitated some components out of the product
stream, thereby changing its chemical composition. As a result, the
product stream in the laboratory model became significantly different from
the product stream in the full scale refinery. Also, the precipitated
products tend to dissolve slowly which leads to a failing of the process
equipment. This limits the temperature range of the model reactor to a
level below that of a full scale ebullated bed reactor. These differences
make it difficult to simulate operation in a full scale ebullated bed
reactor. Of course, many other problems also confront one who attempts to
build a small model refining unit or otherwise simulate a full scale
ebullated bed reactor.
A number of prior art back-mixed reactors have been suggested for
simulating commercial hydrotreating reactors, such as those of Berty,
Carberry, Robinson-Mahoney; see for example J. J. Carberry, Catalysis
Reviews, Vol. 3, pp. 61 et seq. (1961).
In most prior art back-mixed laboratory reactors, the catalyst is placed in
a basket and the liquid phase is agitated by the motion of a basket or an
impeller. Using these designs, it is generally not possible to simulate in
a laboratory model reactor the ratio of catalyst to liquid volumes which
actually appear in a full scale ebullated bed reactor for resid
hydrotreating, which is a very significant factor affecting the yield of
distillable liquids relative to the extent of upgrading of the liquids.
Accordingly, an object of this invention is to provide new and improved
small laboratory models of full scale petroleum refining ebullated bed
reactors, which better simulate the processes occurring in a full scale
refining unit. In particular, an object is to simulate the full scale
commercial operations of an ebullating bed reactor of a resid
hydrotreating unit within a laboratory reactor, without having to either
cool or reheat the product stream before a completion of an entire
processing of the product stream, as well as to predict various operating
conditions and product states based upon changes in the feedstock
composition, catalyst properties, and other conditions.
Another object of the invention is to provide a laboratory model which can
simulate full scale refinery reactor temperatures, gas pressures, and flow
rates. Yet another object is to maintain a volume of catalyst to volume of
reactor fluid ratio in a laboratory model reactor which prevails in a full
scale ebullated reactor. Furthermore, it is desirable to prevent coking
problems which have often plagued prior art laboratory reactors.
Another object of the invention is to operate reactors in the 1000-4000
pound per square inch range of hydrogen pressures.
In keeping with an aspect of the invention, these and other objects are
accomplished by a model reactor hoiusing entirely containing a pump which
can operate at full scale ebullated bed reactor temperatures. An internal
recycle pump and loop is also contained within the model reactor housing
so that the liquid and gaseous streams in the laboratory reactor may be
maintained at full scale commercial reactor temperatures and pressures
without requiring any extraneous cooling and reheating during a refining
process.
Preferred embodiments of the inventive laboratory scale model reactor are
shown in the attached drawing wherein:
FIG. 1 shows an ebullating bed reactor of a full scale ebullated bed
reactor or refining unit which is described in U.S. Pat. No. 4,753,721;
FIG. 2 schematically shows a prior art laboratory scale model reactor
simulator which was supposed to simulate the reactor of FIG. 1;
FIG. 3 shows a gear pump which is used inside the inventive scale model
reactor;
FIG. 4 is a cross section of a first embodiment of an inventive small
model, laboratory reactor simulator;
FIG. 5 is a cross section of a second embodiment of a small model,
laboratory reactor simulator especially designed for easy assembly and
disassembly with provisions for attaining greater temperature stability;
and
FIG. 6 is a cross section of a third embodiment of a small model,
laboratory reactor simulator.
FIG. 1 shows a full scale ebullated bed reactor 20, taken from U.S. Pat.
No. 4,753,721, which discloses a system for processing a high-sulfur resid
oil stream, also known as vacuum-reduced crude, residual oil, or
unhydrotreated virgin resid. The reactor 20 operates continuously at
600.degree. F. to 1000.sup.+ .degree. F. to process resid fed at inlet 22
into the hydrotreating reactor 20, along with a hydrogen-rich gas which is
introduced at inlet 24.
In the reactor 20, the resid is hydroprocessed (hydrotreated) in the
presence of hydrogen and of a fresh or equilibrium hydrotreating catalyst
in order to produce an upgraded effluent product stream, leaving a used
and spent catalyst. Demetalation may occur in the first or subsequent
ebullated bed reactors. Desulfurization may occur in any of many cascaded
ebullated bed reactors in a train of reactors.
Fresh hydrotreating catalyst may be fed downwardly into the top of the
ebullated bed reactor 20 via a fresh catalyst feed line 26. A hot resid
feed and hydrogen-containing feed gases enter the bottom of the ebullated
bed reactor through a common feed line 28 within a plenum chamber
positioned in the interior of the bottom portion of the ebullated bed
reactor. The oil and gas feed are mixed and blended in a homogeneous
manner to distribute the oil and gas in a uniform flow pattern.
The uniform homogeneous mixture of oil and gases flows upwardly through a
grid which helps further to distribute the oil and gas across the reactor
and to prevent the catalyst from falling into the bottom section of the
reactor. An ebullating pump 32 circulates oil from a recycle pan 34
through a downcomer 36 and the grid 30. The circulation rate is sufficient
to lift and expand the catalyst bed from its initial settled level to its
steady state expanded and ebullating level. The effluent product stream of
hydrotreated oil and hydrogen-rich tail gases (off gases) is withdrawn
from the reactor 20 through an effluent product line 38.
Catalyst particles are suspended in a mixture of oil, and hydrogen-rich
feed gases in the reaction zone 42 of the reactor. Typically,
hydrogen-rich gases continually bubble through the oil. The random
ebullating motion of the catalyst particles results in a turbulent mixture
of the phases which promotes good contact mixing and minimizes temperature
gradients.
It should be noted that, during the processing, it is necessary to
circulate and recirculate the product liquid stream within the reactor 20.
More particularly, the product stream enters at 28, rises through the
catalyst bed 42, overflows into downcomer 36, and once again rises through
the catalyst bed 42. When elements in the product stream are displaced by
incoming feed they exit through the effluent product line 38, and are
discharged as the finished product output.
The reactor 20 operates at a hydrotreating temperature of 600.degree. F. to
1000.sup.+ .degree. F. and at a specific volume ratio of catalyst to
liquid. All of the equipment in reactor 20 is specifically designed to
reach and remain at the hydrotreating temperature and pressure. The
product stream never cools or reheats from the time when it first enters
at inlet 28 until it exits at 38. Therefore, in the full scale reactor 20
of FIG. 1, nothing precipitates out of the product stream as a result of
heating, cooling and reheating during processing.
The full scale resid hydrotreating reactor of FIG. 1 is quite flexible. If
desired, the same catalyst may be fed into one or more of the reactors or
a separate demetalation catalyst may be fed into a first reactor while a
different catalyst may be fed to the second or third reactors.
Alternatively, different catalysts may be fed into each of the reactors.
Typically, the spent catalyst contains nickel, sulfur, vanadium, and
carbon (coke). A laboratory model reactor should be equally flexible.
In the past, when an effort has been made to simulate or duplicate full
scale reactor 20 as a laboratory model reactor 50 (FIG. 2), it has not
been possible to carry out all of the process at the same high temperature
and pressure. For example, conventional, commercially available laboratory
pumps have not been able to operate at temperatures greater than about
400.degree. F. Thus, the recycle stream 52, providing an equivalent of
downcomer 36, has been outside the reactor. When a model reactor simulator
50 has an external recycle loop 52 including pump 54, a partially
processed resid oil product effluent is taken from the reactor at outlet
56. While the recycle effluent is in the feed pipe 52, it is cooled to the
400.degree. F. which may be tolerated by pump 54, thereby causing some
elements in the recycle effluent to precipitate out of the feed stream.
The effluent is reheated before or as it is reintroduced into the reactor
at inlet 58. Therefore, when the pump 54 returns the effluent to the
reactor 50, the composition of the product stream is no longer what it was
when it was taken from the outlet 56 or what it will be in the full scale
commercial reactor. Also, the recycle section including line 52 may be
fouled (clogged).
Heretofore, the usual laboratory procedure has been to extrapolate from
data taken at the scale model reactor simulator 50 of FIG. 2 in order to
estimate how the full scale reactor 20 of FIG. 1 would behave if none of
the effluent were ever cooled during the processing. Also, in model
reactor simulator (laboratory reactor) 50, the volume of liquid in line 52
typically contains no catalyst, so reactions occurring here are not
representative of the full scale ebullated bed reactor 20. The
extrapolation has not been as accurate as it should and would be if
cooling and reheating had not occurred in recycle loop 52 and at pump 54
and if non-representative reactions had not occurred.
Another problem is that the approach of FIG. 2 leads to small model
reactors simulators 50 which are much larger than they have to be. For
example, the reactor 50 might be in the order of 8-feet or so tall. There
have been many other and similar practical problems when spent catalyst is
removed and new catalyst is charged into reactor 50. If laboratory
technicians have to remove and handle the reactor 50, as for cleaning,
recharging, repair or maintenance, it is so large and heavy that a great
physical effort is required.
According to the invention, a model reactor simulator (laboratory reactor)
includes everything within a non-magnetic shell so that there never is any
need to cool or reheat any part of the product stream. An internal recycle
pump enclosed within the reactor shell is magnetically driven from outside
the shell so that the high temperature and pressure of a full scale
reactor may be maintained without requiring a penetration of the reactor
shell to operate the pump. Further, according to the invention, the
interior of the reactor and parts therein may be accessed from the top so
that the fluids at the bottom of the reactor do not drain out during
maintenance. The inventive reactor simulator size has been scaled down to
the order of 1 to 2 or 3 feet tall.
A pump which may operate efficiently at 700.degree. F. to 900.degree. F. is
shown in FIG. 3 as including an outer gear 60 and an inner gear 62. This
pump is a commercially available product which is usable at high
temperatures which occur within the reactor. The two gears are not
concentrically mounted with respect to each other so that they turn about
offset axes. As a result, the gear teeth are completely intermeshed on one
side A and completely separated on another side B. At point C, a cavity 64
is beginning to open between the teeth and to draw (suck) in ambient
fluid. As the cavity becomes larger, the teeth of the inner gear 62 pass
behind a shroud 66 to retain the fluid that is drawn into the cavities at
point C. As the gear teeth enter meshing zone A, the cavities begin to
close, as shown at 68, thereby forcing the fluid out of the cavities.
Since this pump is made entirely of an appropriate metal, it may easily
withstand the 700.degree. F. to 900.degree. F. temperature and the high
pressures that may be encountered in a reactor. Moreover, the shaft 70 may
be rotated in response to a turning magnetic field outside the reactor
shell so that the pump may be completely enclosed within the walls of the
reactor shell. Since the shaft does not penetrate the shell wall, there is
no need for any seals about turning shaft 70, at any point on the reactor
wall.
A first embodiment of the inventive small model, laboratory reactor
simulator is shown in FIG. 4, which is a reactor that is, roughly
speaking, about two feet tall. At the top of the reactor simulator, a
magnetic drive is arranged to turn the pump in response to an external
rotating magnetic field without requiring a penetration of the reactor
shell.
In greater detail, a non-magnetic (such as stainless steel) housing 72 is
integrally joined to a pipe 74 which, in turn, is joined to the laboratory
reactor by a suitable gland 76 and a suitable packing 78. Therefore, the
interior of housing 72 is at about the same pressure, temperature, and
environment that prevails inside the reactor shell. The housing 72
contains a magnetic drive 80 for turning shaft 70 of the pump 112 (also
shown in FIG. 3). There are little or no differential temperatures and
pressures so that all equipment inside housing 72 can withstand the
prevailing reactor pressure, temperature, and environment. A suitable
shaft bearing 81 supports the pump shaft. The magnetic drive is mounted
outside the heated reaction zone 83 to isolate the drive from the
hydrotreating temperatures and pressures of the reaction zone. Thus, there
are none of the problems which were associated with pump 54 (FIG. 2) of
prior laboratory model reactor simulators.
The magnetic drive 80 is rated to be operative up to 6000 psi and
650.degree. F. This rating is more than adequate for a model reactor. In
one case, an Autoclave Engineers "Magnadrive II", Model No. 1.5001AS06C
was used. Other suitable drives can be used.
Advantageously, the laboratory reactors of this invention reasonably
simulate the actual operating conditions of a full scale commercial
ebullated bed reactor, such as those operated at the Amoco Oil Company
Refinery at Texas City, Tex.
The main element of the reactor shell or body is a seamless pipe 82 that
may be made in any suitable length and diameter. The catalyst is located
in a catalyst bed 85 in the reaction zone 83. The seamless pipe 82 was six
and three-quarters inches long and 1.503 inches inside diameter, in one
embodiment. The remainder of the reactor shell was made of commercially
available units 84-98 which are sold under the trademark "Grayloc". The
units 84, 98 are known as hubs; units 92, 94 as butt weld hubs; and unit
88 as a spool piece. The butt weld hubs 92, 94 are welded at 95, 95 to
opposite ends of pipe 82.
Each of these Grayloc units has a flaring end flange 100, 102 which may be
placed in an end-to-end confrontation with a suitable seal ring
therebetween, as shown at 104. While in this position two semicircular
clamps 86 may be positioned on opposite sides of the flanges 100, 102 to
completely surround them. The inside diameters of the clamps have a groove
110 with a somewhat triangular frustum cross section which is
complementary to the shapes of the confronting flanges. Bolt holes 106,
108 on opposite ends of the semi-circular clamps enable them to be bolted
together. As the two clamps are drawn together by tightening the bolts in
the bolt holes 106, 108, the end flanges 100, 102 are wedged together and
against sealing ring 104 by the closing of grooves 110. Other types of
fasteners and closures may be used, if desired.
The resulting structure is a reactor shell which is a miniature version of
a hydrotreating reactor. The shell may be completely disassembled and
reassembled whenever one wishes to replace the catalyst, or wishes to
build and test new internal reactor structures, or wishes to have ready
access to the interior of the reactor for any other reason.
Inside the reactor shell, an internal recycle pump means 112 causes a
suction at the top of pipe 114 and pressure at the top of pipe 116,
thereby causing a portion of the product stream within the reactor shell
to flow up pipe 114, cross over through the pump, and flow down pipe 116
for circulating and recirculating (recycling) the product stream
vertically through the catalyst bed. After the fluid reaches the bottom of
pipe 116, it passed upwardly through the catalyst bed 85. The speed and
amount of recirculation of the product stream may be selected and
controlled by selecting and controlling the pump speed. The selection and
control may be carried out under the control of a microprocessor 117 or
other suitable means.
Internal screens at 118 and 120 set off a reaction zone or area of the
reactor shell for containing a catalyst between them. The preferred
heterogeneous hydrotreating catalyst has a consistency which is somewhat
similar to pellets or a very coarse sand. A well 122 in the form of a pipe
with a closed end is located around the intake end of pipe 114 to keep the
catalyst from entering the pump.
The fluid within the reactor rises through screens 120, 118 and overflows
into the well 122 from which a portion of it is pumped through pipes 114,
116 back to the bottom of the reactor so that it may rise again through
the catalyst. This circulation and recirculation (recycling) continues
until at least a portion of the fluid is displaced by the feed entering
feed line 126, with the displaced fluid (product) exiting through overflow
product outlet line 124, from which it is discharged.
The input oil feed stream flows into the reactor shell via an intake oil
feed line or pipe 126. A stream of hydrogen gas and/or light hydrocarbon
gases can be fed into the reactor shell via a gas feed line or pipe 128.
Alternatively, the hydrogen-containing feed gas (hydrogen and/or light
hydrocarbon gases) can be combined (mixed) and fed with the oil feed
through the oil feed line 126.
Thus, the internal recycle pump provides a means for back mixing the oil
feed and gas while in the presence of the catalyst and under a catalyst to
liquid ratio and at a pressure and temperature substantially similar to a
ratio, pressure, and temperature used in said full scale reactor.
A nipple 130 is welded at 132 to the Grayloc hub 98 in order to receive any
suitable sensors, instrumentation, or the like. In this particular
embodiment, the sensor is a thermocouple inside a stainless steel tube
134, which is held in place by a gland 136 which is threaded into nipple
130. In one embodiment, a thermocouple in a thermowell was used to measure
internal reactor temperature.
A most attractive feature of the embodiment of FIG. 4 is that a laboratory
technician may build and rebuild the reactor any number of times with a
maximum flexibility of design choices. Thus, this embodiment is a most
attractive vehicle for catalyst evaluation.
A second embodiment of a laboratory model reactor simulator (FIG. 5) is
similar to the first embodiment of FIG. 4. Since the same reference
numerals are used to designate the same parts, they will not be explained
a second time.
The upper hub 84 has a dependent nipple 140 joined thereto at welds 142.
The upper hub may also be threaded or clamped. The lower part of this
nipple 140 is threaded at 144 to receive a dependent tube 146. The outside
diameter of tube 146 is slightly smaller than the inside of tube 82 so
that it slides therein, with a telescoping motion. The intake pipe 114 is
permanently attached to the assembly 156. Below pump 112 is a slip joint
150 which slides over and makes a connection with the discharge pipe 116.
Therefore, when the bolts are removed from bolt holes 106, 108, the two
semi-circular clamps 86 may be pulled away from flanges 100, 102. Then,
the top of the reactor shell may be pulled upwardly and tube 146 slides
out of tube 82. The discharge pipe 116 is disconnected from the pump at
slip joint 150. Thus, the entire pump assembly 152 may be lifted off and
cleaned, repaired, or replaced, as may be required; or catalyst can be
replaced or added to the reaction zone 83.
Also, while the pump assembly 152 is removed, there is access to the upper
interior of the reactor shell. If, for any reason, it is necessary to
replace pump 112 or the slip fitting 150, two or more hex head socket
screws 152, 154 may be removed so that the block 156 may be lifted off.
Another difference between the embodiments of FIGS. 4, 5 is the combining
of the oil fill inlet 126 and hydrogen purge tap 128 into a single input
158. This makes the intake into the reactor shell of FIG. 5 a little more
like the inlet 50 in U.S. Pat. No. 4,753,721.
A deadman spacer 160 in the form of a metal element has been added in the
bottom of the second embodiment reactor shell (FIG. 5) in order to provide
greater thermal stability. The spacer 160 is held in place by a collar 162
designed to fit into a space provided for that purpose in the Grayloc
elements 94, 98. Therefore, if the clamp 96 is removed, the spacer 160
simply slides out. The spacer 160 helps isolate the reaction zone 83 from
the Grayloc closure 96 which can liberate heat rapidly. Thus, the spacer
160 serves to keep the catalyst bed 85 at the desired temperature. Also,
removal of the spacer 160 gives access to the lower interior of the
reactor shell.
Another modification found in FIG. 5 as compared to FIG. 4 is the use of
Autoclave Engineers "Slimline" hardware 164 which makes it easier to
change or replace thermowells used inside the reactor.
FIG. 6 shows yet another embodiment of the inventive laboratory model
reactor simulator which is a modified commercial product sold under the
commercial designation Autoclave Engineers 300 c.c. stirred autoclave
Model BC0030SS05AH which may be purchased with a magnadrive.
This is the smallest of the three embodiments having an overall reactor
height in the nature of ten and three-eighths inches, plus the heights of
the magnadrive 170 and thermowell assembly 164. The entire unit is mounted
on a support plate 172. The autoclave housing 174 has been modified by an
addition of an intake tube 158 and outlet or overflow tube 124.
Those elements in the embodiment of FIG. 6, which have already been
explained in connection with the embodiments of FIGS. 4 and 5, have been
given the same reference numerals and will not be explained again.
The element 146 extends from mounting head to the slip joint 150 so that it
may lift or slide away from the flange of the autoclave housing. The
sliding element is held in place by at least two hex head cap screws 178,
180 which are tightly drawn to approximately 40-50 foot/pounds of torque.
The catalyst fills catalyst bed (space) 185 between upper and lower screens
118, 120.
In each of the three embodiments, means are provided for feeding and
removing catalyst from the reactor zone. More particularly, in FIG. 4, the
"Grayloc" clamps 86, 90 are removed. The upper sections 72, 88 are lifted
off, as a unit, and a measured amount of catalyst is either implaced or
removed from the reaction zone 83. In the embodiment of FIG. 5, the
"Grayloc" clamp 86 is removed and the upper unit is pulled so that tube
146 may be slid out of tube 82, after which catalyst may be added to or
removed from reactor zone 83. In the embodiment of FIG. 6, the hex head
cap screws 178, 180 are removed. Unit 146 is removed and catalyst is added
to or removed from the reactor zone 185. After the correct amount of
catalyst is in place, the process is reversed and the small model reactor
is reassembled, to the form shown in the several figures.
In operation, the three embodiments can operate substantially similar to a
full scale commercial ebullated bed reactor of a resid hydrotreating unit.
Therefore, the procedures and process that are followed in the inventive
laboratory model will not be described in detail. The experimenter may
vary the catalysts, temperature, pressure, ratio of catalyst to liquids,
etc. and know that the laboratory results will be substantially duplicated
when they are adopted in the full scale refinery.
Those who are skilled in the art will readily perceive how to modify the
invention. Therefore, the appended claims are to be construed to cover all
equivalents which fall within the true scope and spirit of the invention.
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